Area fraction determination of plate to be printed - by using selectively operated photoelectric elements and masking screens

摘要

The size of the effective measuring are (8) can be precisely adjusted to the size of the ink zone to be measured by switching on photoelectric elements (7) lying within this area using a switch in the measurement circuit and by using movable screens (9). The effective measuring area (8) is less than or equal to the total area (6) formed by the photoelectric elements. The screens (9) are moved by e.g. magnts or stepping motors. The photoelectric elements are connected in parallel and can be operated individually or in groups.